THE HAMILTON ASSOCIATION. 3 
[Extracted from the GEOLOGICAL MAGAZINE, Decade V., Vol. I, No. 483, 
September, 1904. ] 
NOTE ON A PALZOZOIC CYPRIDINA FROM CANADA. 
By Professor T. RUPERT JONES, F.R.S., F.G.S. 
es the Annals and Magazine of Natural History, ser. vii, vol. i (1898), pp. 
333-334, pl. xxvii, a numerous series of fossil Ostracoda, with bivalved 
carapaces, having more or less resemblance to those of Cypridina, were 
described and figured. The specimens selected had been collected by va- 
rious observers in different regions, and comprised two from the Tertiary 
of France, two from the Cretaceous of Belgium, one from the Permian of 
Durham, seven from the Carboniferous of Britain, three from the Devon- 
ian of Devon, three from the Upper Silurian and two from the Lower Si- 
lurian (Ordovician) of distant regions. References were made to several 
allied Palaeozoic forms; and one other species from the Carboniferous of 
North America (Ulrich) and two from the Upper Silurian of Scania (Mo- 
berg) ought to have been mentioned. 
We have now to notice another old Cypridinal form (the internal cast 
of a left valve), probably of Ordovician age. It has come to hand from 
Col. C. C. Grant, of Hamilton, Ontario, Canada, who exposed it in break- 
ing up some blocks of limestone, probably belonging to the Trenton 
series, from a ‘‘ glacial drift” at Winona, on the shore of Lake Ontario, 
not far from Hamilton. 
This limestone is largely composed of a small gregarious variety of 
Isochilina Ottawa, Jones (see GEOL. MaAaG., July, 1903, pp. 300-304) ; and in 
this condition it resembles other specimens collected by Colonel Grant,, 
and sent by him to the British Museum. 
The particular specimen under notice approaches in lateral outline to 
Cypridina brevimentum, Jones, Kirkby, and Brady (Foss. Entom. Car- 
bonif., pt. i, 1874, p. 16, pl. ii, figs. 15-19, especially fig. 15a). It differs, 
however, from that species in the following particulars : 
It is more definitely oblong ; straight on the back, with its postero- 
dorsal angle, and not the postero-ventral part, projecting. The hook or 
